When the documentation is published to http://api.instructure.com/ the
link to http://canvas.docker isn't valid, making it host relative means
it works in both places.
Closes gh-1288
Change-Id: Ifdaaf01435f739c16a08fcce8e1922b05df0e0ea
Reviewed-on: https://gerrit.instructure.com/149907
Tested-by: Jenkins
Reviewed-by: Derek Bender <djbender@instructure.com>
Product-Review: Omar Khan <okhan@instructure.com>
QA-Review: Omar Khan <okhan@instructure.com>
8e783843ea